Characterization, corrosion behavior, cellular response and in vivo bone tissue compatibility of titanium-niobium alloy with low Young's modulus

Biodegradable polyvinyl alcohol/nano-hydroxyapatite composite membrane enhanced by MXene nanosheets for guided bone regeneration

MXene, as a new category of two-dimensional nanomaterials, exhibits a promising prospect in biomedical applications due to its ultrathin structure and morphology, as well as a range of remarkable properties such as biological, chemical, electronic, and optical properties. In this work, different concentrations of MXene (M) were added to polyvinyl alcohol (PVA, P)/nano-hydroxyapatite (n-HA, H) mixed solution, and series of PVA/n-HA/MXene (PHM) composite membranes were obtained by combining sol-gel and freeze-drying processes. Morphology, chemical composition, surface, and mechanical properties of the prepared PHM membranes were characterized by various techniques. Subsequently, the swelling and degradation performances of the composite membranes were tested by swelling and degradation tests. In addition, in vitro studies like cell adhesion, cytotoxicity, proliferation, osteogenic differentiation, and antibacterial properties of MC3T3-E1 were also evaluated. The results showed that the addition of MXene could apparently improve the composite membranes' physicochemical properties, bioactivity, and osteogenic differentiation. Specially, PHM membrane had the best comprehensive properties when the concentration of MXene was set as 2.0% w/v. In a word, the addition of MXene has a positive effect on improving the mechanical properties, osteogenic induction, and antibacterial properties of PH composite membranes, and the prepared PHM composite membranes possess potential applications for guided bone regeneration.

In situ production of low-modulus Ti-Nb alloys by selective laser melting and their functional assessment toward orthopedic applications

This work aimed to manufacture Ti-28.5Nb and Ti-40.0Nb (wt%) alloys in situ via selective laser melting (SLM) from Ti and Nb elemental powders. X-ray diffraction analysis revealed complete β-phase (cubic) in Ti-40.0Nb and a mixture of (α'' orthorhombic + β cubic) phases in Ti-28.5Nb were formed, whereas few of the Nb particles remained only partially fused during manufacturing. The fraction of partially melted Nb particles was determined as ∼2 and ∼18% in Ti-28.5Nb and Ti-40Nb, respectively. Mechanical characterization revealed higher hardness and more strength in Ti-28.5Nb than in Ti-40.0Nb due to the presence of the α'' phase in the former. Tribocorrosion tests reveal a significantly better wear-corrosion resistance for Ti-40.0Nb, as determined from a lower total volume loss in Ti-40.0Nb (∼2 × 10-4 mm-3) than in Ti-28.5Nb (∼13 × 10-2 mm-3). The lower volume loss and better corrosion resistance behavior are attributed to the β phase, which was dominant in Ti-40.0Nb. Cell studies reveal no toxicity for up to 7 days. Both the alloys were better at supporting cell proliferation than wrought Ti6Al4V. This study presents a route to preparing Ti-Nb alloys in situ by SLM that are promising candidates for biomedical applications.

Albumin suppresses oxidation of TiNb alloy in the simulated inflammatory environment

Literature data has shown that reactive oxygen species (ROS), generated by immune cells during post-operative inflammation, could induce corrosion of standard Ti-based biomaterials. For Ti6Al4V alloy, this process can be further accelerated by the presence of albumin. However, this phenomenon remains unexplored for Ti β-phase materials, such as TiNb alloys. These alloys are attractive due to their relatively low elastic modulus value. This study aims to address the question of how albumin influences the corrosion resistance of TiNb alloy under simulated inflammation. Electrochemical and ion release tests have revealed that albumin significantly enhances corrosion resistance over both short (2 and 24 h) and long (2 weeks) exposure periods. Furthermore, post-immersion XPS and cross-section TEM analysis have demonstrated that prolonged exposure to an albumin-rich inflammatory solution results in the complete coverage of the TiNb surface by a protein layer. Moreover, TEM studies revealed that H2O2-induced oxidation and further formation of a defective oxide film were suppressed in the solution enriched with albumin. Overall results indicate that contrary to Ti6Al4V, the addition of albumin to the PBS + H2O2 solution is not necessary to simulate the harsh inflammatory conditions as could possibly be found in the vicinity of a TiNb implant.

Study on 3D printed MXene-berberine-integrated scaffold for photo-activated antibacterial activity and bone regeneration

The repair of mandibular defects is a challenging clinical problem, and associated infections often hinder the treatment, leading to failure in bone regeneration. Herein, a multifunctional platform is designed against the shortages of existing therapies for infected bone deficiency. 2D Ti3C2 MXene and berberine (BBR) are effectively loaded into 3D printing biphasic calcium phosphate (BCP) scaffolds. The prepared composite scaffolds take the feature of the excellent photothermal capacity of Ti3C2 as an antibacterial, mediating NIR-responsive BBR release under laser stimuli. Meanwhile, the sustained release of BBR enhances its antibacterial effect and further accelerates the bone healing process. Importantly, the integration of Ti3C2 improves the mechanical properties of the 3D scaffolds, which are beneficial for new bone formation. Their remarkable biomedical performances in vitro and in vivo present the outstanding antibacterial and osteogenic properties of the Ti3C2-BBR functionalized BCP scaffolds. The synergistic therapy makes it highly promising for repairing infected bone defects and provides insights into a wide range of applications of 2D nanosheets in biomedicine.

Green synthetic sodium alginate-glycerol-MXene nanocomposite membrane with excellent flexibility and mineralization ability for guided bone regeneration

Developing a novel bioactive material as a barrier membrane for guided bone regeneration (GBR) surgery remains challenging. As a new member of two-dimensional (2D) material family, MXene is a promising candidate component for barrier membranes due to its high specific surface area and osteogenic differentiation ability. In this work, a green and simple SA/glycerol/MXene (SgM) composite membrane was prepared via solvent casting method by using sodium alginate (SA) and MXene (M) as raw materials while employing glycerol (g) as a plasticizer. The addition of glycerol significantly increased the elongation at the break of SA from 10%-20% to 240%-360%, while the introduction of MXene promoted the deposition of calcium and phosphorus to form hydroxyapatite. At the same time, the roughness of the SgM composite membrane is apparently improved, which is conducive to cell adhesion and proliferation. This work provides a basis for further research on SgM composite membrane as GBR membrane for the treatment of bone defects.

Synergistic Amelioration of Osseointegration and Osteoimmunomodulation with a Microarc Oxidation-Treated Three-Dimensionally Printed Ti-24Nb-4Zr-8Sn Scaffold via Surface Activity and Low Elastic Modulus

Biomaterial scaffolds, including bone substitutes, have evolved from being primarily a biologically passive structural element to one in which material properties such as surface topography and chemistry actively direct bone regeneration by influencing stem cells and the immune microenvironment. Ti-6Al-4V(Ti6Al4V) implants, with a significantly higher elastic modulus than human bone, may lead to stress shielding, necessitating improved stability at the bone-titanium alloy implant interface. Ti-24Nb-4Zr-8Sn (Ti2448), a low elastic modulus β-type titanium alloy devoid of potentially toxic elements, was utilized in this study. We employed 3D printing technology to fabricate a porous scaffold structure to further decrease the structural stiffness of the implant to approximate that of cancellous bone. Microarc oxidation (MAO) surface modification technology is then employed to create a microporous structure and a hydrophilic oxide ceramic layer on the surface and interior of the scaffold. In vitro studies demonstrated that MAO treatment enhances the proliferation, adhesion, and osteogenesis capabilities on the scaffold surface. The chemical composition of the MAO-Ti2448 oxide layer is found to enhance the transcription and expression of osteogenic genes in bone mesenchymal stem cells (BMSCs), potentially related to the enrichment of Nb2O5 and SnO2 in the oxide layer. The MAO-Ti2448 scaffold, with its synergistic surface activity and low stiffness, significantly activates the anti-inflammatory macrophage phenotype, creating an immune microenvironment that promotes the osteogenic differentiation of BMSCs. In vivo experiments in a rabbit model demonstrated a significant improvement in the quantity and quality of the newly formed bone trabeculae within the scaffold under the contact osteogenesis pattern with a matched elastic modulus. These trabeculae exhibit robust connections to the external structure of the scaffold, accelerating the formation of an interlocking structure between the bone and implant and providing higher implantation stability. These findings suggest that the MAO-Ti2448 scaffold has significant potential as a bone defect repair material by regulating osteoimmunomodulation and osteogenesis to enhance osseointegration. This study demonstrates an optional strategy that combines the mechanism of reducing the elastic modulus with surface modification treatment, thereby extending the application scope of β-type titanium alloy.

Multifunctional MXene-Based Bioactive Materials for Integrated Regeneration Therapy

The reconstruction engineering of tissue defects accompanied by major diseases including cancer, infection, and inflammation is one of the important challenges in clinical medicine. The development of innovative tissue engineering strategies such as multifunctional bioactive materials presents a great potential to overcome the challenge of disease-impaired tissue regeneration. As the major representative of two-dimensional nanomaterials, MXenes have shown multifunctional physicochemical properties and have been diffusely studied as multimodal nanoplatforms in the field of biomedicine. This review summarized the recent advances in the multifunctional properties of MXenes and integrated regeneration-therapy applications of MXene-based biomaterials, including tissue regeneration-tumor therapy, tissue regeneration-infection therapy, and tissue regeneration-inflammation therapy. MXenes have been recognized as good candidates for promoting tissue regeneration and treating diseases through photothermal therapy, regulating cell behavior, and drug and gene delivery. The current challenges and future perspectives of MXene-based biomaterials in integrated regeneration-therapy are also discussed well in this review. In summary, MXene-based biomaterials have shown promising potential for integrated tissue regeneration and disease treatment due to their favorable physicochemical properties and bioactive functions. However, there are still many obstacles and challenges that must be addressed for the regeneration-therapy applications of MXene-based biomaterials, including understanding the bioactive mechanism, ensuring long-term biosafety, and improving their targeting therapy capacity.

Biodegradable and biocompatible alginate/gelatin/MXene composite membrane with efficient osteogenic activity and its application in guided bone regeneration

Guided bone regeneration (GBR) utilizes a barrier membrane to maintain the osteogenic space and promote osseointegration of the implants. Developing a novel biomaterial to meet the mechanical and biological performance requirements of GBR membrane (GBRM) remains a huge challenge. Here, the sodium alginate (SA, S)/gelatin (G)/MXene (M) composite membrane (SGM) was prepared by combining sol-gel and freeze-drying processes. The incorporation of MXene improved the mechanical properties and hydrophilicity of the SA/G (SG) membrane, and also enhanced its cell proliferation and osteogenic differentiation. More importantly, when the concentration of MXene is 0.25%W/V, the SGM composite membrane exhibited the best tensile strength (40 MPa), high swelling rate (1012%), and appropriate degradation rate (40%). Meanwhile, the biological improvements were more significant. Therefore, the appropriate amount addition of MXene has a positive and obvious effect on the improvements of the mechanical properties, biocompatibility, and osteogenic induction of the SG composite membranes. This work provides a more extendable development idea for the application of SGM composite membrane as GBRM.

Influence of antibacterial surface treatment on dental implants on cell viability: A systematic review

There is no consensus in the literature about the best non-cytotoxic antibacterial surface treatment for dental implants. Critically evaluate the existing literature and answer the question: "which surface treatment for dental implants made of titanium and its alloys has the greatest non-cytotoxic antibacterial activity for osteoblastic cells?" This systematic review was registered in the Open Science Framework (osf.io/8fq6p) and followed the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols. The search strategy was applied to four databases. Articles were selected that evaluated in both studies the properties of 1) antibacterial activity and 2) cytotoxicity on osteoblastic cells of titanium and their alloy dental implants when treated superficially. Systematic reviews, book chapters, observational studies, case reports, articles that studied non-dental implants, and articles that evaluated only the development of surface treatment were excluded. The Joanna Briggs Institute, a quasi-experimental study assessment tool, was adapted to assess the risk of bias. The search strategy found 1178 articles in the databases after removing duplicates in EndNote Web, resulting in 1011 articles to be evaluated by title and abstract, of which 21 were selected for full reading, of which 12 were included by eligibility criteria, and nine were excluded. Quantitative synthesis could not be performed due to the heterogeneity of the data (surface treatment, antibacterial assay, bacteria strain, cell viability assay, and cell type). Risk of bias assessment showed that ten studies were classified as low risk and two studies as moderate risk. The evaluated literature allowed us to conclude that: 1) The literature surveyed did not allow answering the question due to the heterogeneity of the studies; 2) Ten of the 12 studies evaluated presented surface treatments with non-cytotoxic antibacterial activity; 3) Adding nanomaterials, QPEI, BG, and CS, reduce the chances of bacterial resistance by controlling their adhesion by electrical forces.

Additively Manufactured MAX- and MXene-Composite Scaffolds for Bone Regeneration- Recent Advances and Future Perspectives

Human bones can suffer from various injuries, such as fractures, bone cancer, among others, which has initiated research activities towards bone replacement using advanced bio-materials. However, it is still challenging to design bio-scaffolds with bone-inducing agents to regenerate bone defects. In this regard, MAX-phases and MXenes (early transition metal carbides and/or nitrides) have gained notable attention due to their unique hydrophilicity, bio-compatibility, chemical stability, and photothermal properties. They can be used in bone tissue engineering as a suitable replacement or reinforcement for common bio-materials (polymers, bio-glasses, metals, or hydroxyapatite). To fabricate bio-scaffolds, additive manufacturing is prospective due to the possibility of controlling porosity and creating complex shapes with high resolution. Until now, no comprehensive article summarizing the existing state-of-the-art related to bone scaffolds reinforced by MAX-phases and MXenes fabricated by additive manufacturing has been published. Therefore, our article addresses the reasons for using bone scaffolds and the importance of choosing the most suitable material. We critically discuss the recent developments in bone tissue engineering and regenerative medicine using MAX-phases and MXenes with a particular emphasis on manufacturing, mechanical properties, and bio-compatibility. Finally, we discuss the existing challenges and bottlenecks of bio-scaffolds reinforced by MAX-phases and MXenes before deriving their future potential.

Recent advances in 2D metal carbides and nitrides (MXenes): synthesis and biological application

As a new two-dimensional (2D) material, transition metal carbides and nitrides (MXenes) have attracted much attention because of their excellent physical and chemical properties. In recent years, MXenes have been widely applied in the biological field due to their high biocompatibility, abundant surface groups, good conductivity, and photothermal properties. Here, the main synthesis methods of MXenes and the analysis of the advantages and disadvantages of each method are presented in detail. Then, the latest developments of MXenes in the biological field, including biosensing, antibacterial activity, reactive oxygen species (ROS) and free radical scavenging, tissue repair and antitumor therapy are comprehensively reviewed. Finally, the current challenges and future development trends of MXenes in biological applications are discussed.

The interface stiffness and topographic feature dictate interfacial invasiveness of cancer spheroids

During cancer metastasis, tumor cells likely navigate, in a collective manner, discrete tissue spaces comprising inherently heterogeneous extracellular matrix microstructures where interfaces may be frequently encountered. Studies have shown that cell migration modes can be determined by adaptation to mechanical/topographic cues from interfacial microenvironments. However, less attention has been paid to exploring the impact of interfacial mechnochemical attributes on invasive and metastatic behaviors of tumor aggregates. Here, we excogitated a collagen matrix-solid substrate interface platform to investigate the afore-stated interesting issue. Our data revealed that stiffer interfaces stimulated spheroid outgrowth by motivating detachment of single cells and boosting their motility and velocity. However, stronger interfacial adhesive strength between matrix and substrate led to the opposite outcomes. Besides, this interfacial parameter also affected the morphological switch between migration modes of the detached cells and their directionality. Mechanistically, myosin II-mediated cell contraction, compared to matrix metalloproteinases-driven collagen degradation, was shown to play a more crucial role in the invasive outgrowth of tumor spheroids in interfacial microenvironments. Thus, our findings highlight the importance of heterogeneous interfaces in addressing and combating cancer metastasis.

A Review of Research Progress in Selective Laser Melting (SLM)

SLM (Selective Laser Melting) is a unique additive manufacturing technology which plays an irreplaceable role in the modern industrial revolution. 3D printers can directly process metal powder quickly to obtain the necessary parts faster. Shortly, it will be possible to manufacture products at unparalleled speeds. Advanced manufacturing technology is used to produce durable and efficient parts with different metals that have good metal structure performance and excellent metal thermal performance, to lead the way for laser powder printing technology. Traditional creative ways are usually limited by time, and cannot respond to customers' needs fast enough; for some parts with high precision and complexity, conventional manufacturing methods are inadequate. Contrary to this, SLM technology offers some advantages, such as requiring no molds this decreases production time and helps to reduce costs. In addition, SLM technology has strong comprehensive functions, which can reduce assembly time and improve material utilization. Parts with complex structures, such as cavities and three-dimensional grids, can be made without restricting the shape of products. Products or parts can be printed quickly without the use of expensive production equipment. The product quality is better, and the mechanical load performance is comparable to traditional production technologies (such as forging). This paper introduces in detail the process parameters that affect SLM technology and how they affect SLM, commonly used metal materials and non-metallic materials, and summarizes the current research. Finally, the problems faced by SLM are prospected.

Titanium Coated with Graphene and Niobium Pentoxide for Biomaterial Applications

Graphene and niobium oxide are used in biomaterial coatings. In this work, commercially pure titanium (cp Ti) was coated with graphene oxide (GO), niobium pentoxide (Nb₂O₅), and a mixture of both materials (NbGO) by the electrochemical deposition method. The surface morphology, roughness, wettability, and degradation of coated and uncoated samples were analyzed by scanning electron microscopy, interferometry, and contact angle. The results showed that the specimens coated with NbGO (cp Ti-NbGO) showed the highest surface roughness (Ra = 0.64 μm) and were hydrophobic. The contact (θ) angle between water and the surface of uncoated specimens (cp Ti), coated with GO (cp Ti-GO), coated with a mixture with GO and Nb₂O₅) (cp Ti-NbGO), and coated with Nb₂O₅ were 50.74°, 44.35°, 55.86°, and 100.35°, respectively. The electrochemical corrosion tests showed that coating with graphene oxide increased the corrosion resistance and coating with Nb₂O₅ decreased the corrosion resistance. The negative effect of the effect of Nb₂O₅ coating in corrosion resistance compensated for the release of Nb₂O₅, which helps osseointegration, increasing cell viability, and proliferation of osteoblasts. The NbGO coating may be a good way to combine the bactericidal effect of graphene oxide with the osseointegration effect of Nb₂O₅.

Biocompatibility of a Ti-Rich Medium-Entropy Alloy with Glioblastoma Astrocytoma Cells

Titanium and titanium alloys are widely used in medical devices and implants; thus, the biocompatibility of these metals is of great importance. In this study, glioblastoma astrocytoma cellular responses to Ti₆₅-Zr₁₈-Nb₁₆-Mo₁ (Ti65M, metastable medium-entropy alloy), Ti-13Nb-7Sn-4Mo (TNSM, titanium alloy), and commercially pure titanium (CP-Ti) were studied. Several physical parameters (crystal phase structure, surface roughness and hardness) of the titanium alloys were measured, and the correlation with the cellular viability was investigated. Finally, the relative protein expression in cellular proliferation pathways was measured and compared with mRNA expression assessed with quantitative real-time reverse transcription polymerase chain reaction assay (qRT-PCR).

Experimental Research on New Developed Titanium Alloys for Biomedical Applications

The mechanical properties and electrochemical behavior of two new titanium alloys, Ti20Mo7Zr and Ti20Mo7Zr0.5Si, are investigated in this paper. The alloys have been manufactured by vacuum arc remelting (VAR) technique and studied to determine their microstructure, corrosion behavior, and mechanical properties. Metallographic observations and quantitative microanalysis by optical microscopy, scanning electron microscopy SEM, and energy dispersive X-rays spectroscopy EDX were performed. Data about the three-point bending test and microhardness are presented. For electrochemical properties, three different environments were used: Ringer solution at 25 °C, Ringer solution at 40 °C simulating fever condition, and 3.5% NaCl solution. Metallographic investigation revealed the biphasic and dendritic structure of both samples when the procedures were performed. Electrochemical testing in body simulation fluid, fever conditions, and saline medium showed that the lower the proportion of silicon in the samples, the higher the corrosion resistance. The formation of a titanium oxide layer on the surface of both samples was noticed using quantitative EDX analysis. The three-point bending test for the two samples revealed that the presence of silicon decreases the modulus of elasticity; the surface of the samples displayed soft and hard phases in the microhardness test. Electrochemical impedance spectroscopy (EIS) measurements were carried out at different potentials, and the obtained spectra exhibit a two-time constant system, attesting double-layer passive film on the samples.

Laser-Deposited Beta Type Ti-42Nb Alloy with Anisotropic Mechanical Properties for Pioneering Biomedical Implants with a Very Low Elastic Modulus

Present commercial titanium alloy implants have an elastic modulus higher than 100 GPa, whereas that of the cortical bone is much smaller (17−28 GPa). This elastic modulus mismatch produces a stress shielding effect and the resorption of the bone surrounding the implant. In the present work, a <100> fiber texture is developed in β type Ti-42Nb (wt%) alloy ingots generated by laser-directed energy deposition (LDED) in order to achieve anisotropic mechanical properties. In addition, we demonstrate that laser-deposited β type Ti-42Nb alloy ingots with an intense <100> fiber texture exhibit a very low elastic modulus in the building direction (Ez < 50 GPa) and high yield (σ0.2z > 700 MPa) and tensile (UTSz > 700 MPa) strengths. Laser-deposited Ti-42Nb alloy enhances the osteoinductive effect, promoting the adhesion, proliferation, and spreading of human osteoblast-like cells. Hence, we propose that laser-deposited β type Ti-42Nb alloy is a potentially promising candidate for the manufacturing of pioneering biomedical implants with a very low elastic modulus that can suppress stress shielding.

In Vitro Molecular Study of Titanium-Niobium Alloy Biocompatibility

Titanium dental implants have common clinical applications due to their biocompatibility, biophysical and biochemical characteristics. Although current titanium is thought to be safe and beneficial for patients, there are several indications that it may release toxic metal ions or metal nanoparticles from its alloys into the surrounding environment, which could lead to clinically relevant complications including toxic reactions as well as immune dysfunctions. Hence, an adequate selection and testing of medical biomaterial with outstanding properties are warranted. This study was designed to explore the biocompatibility of smooth titanium-niobium alloy (S_TiNb) versus smooth titanium commercially pure (S_TiCp)—a reference in implantology. All experiments were performed in vitro using human osteoblast-like SaOs-2 and monocyte THP-1 cell lines as models. Cell adhesion and growth morphology were determined by scanning electron microscopy, while cell viability was evaluated using WST-1 assay. Because niobate anions or niobium nanoparticles can be released from implants during biomaterial-cell interaction, potential immunotoxicity of potassium niobate (KNbO₃₎ salt was evaluated by examining both metabolic activity and transcriptomic profiling of treated THP-1 monocytes. The main findings of this study are that S_TiCp and S_TiNb discs do not show an impact on the proliferation and viability of SaOs-2 cells compared to polystyrene surfaces, whereas a significant decrease in THP-1 cells’ viability and metabolic activity was observed in the presence of S_TiNb discs compared to the control group. However, no significant changes were found neither at the metabolic activity nor at the transcriptomic level of THP-1 monocytes exposed to KNbO₃ salt, suggesting that niobium has no effect on the immune system. Overall, these data imply a possible toxicity of S_TiNb discs toward THP-1 cells, which may not be directly related to niobium but perhaps to the manufacturing process of titanium-niobium alloy. Thus, this limitation must be overcome to make titanium alloy an excellent material for medical applications.

3D printing of MXene composite hydrogel scaffolds for photothermal antibacterial activity and bone regeneration in infected bone defect models

The repair of infected bone defects with irregular shapes is still a challenge in clinical work. Infected bone defects are faced with several major concerns: the complex shapes of bone defects, intractable bacterial infection and insufficient osseointegration. To solve these problems, we developed a personalized MXene composite hydrogel scaffold GelMA/β-TCP/sodium alginate (Sr²⁺)/MXene (Ti₃C₂) (GTAM) with photothermal antibacterial and osteogenic abilities by 3D printing. In vitro, GTAM scaffolds could kill both Gram-positive and Gram-negative bacteria by NIR irradiation due to the excellent photothermal effects of MXene. Furthermore, rat bone marrow mesenchymal stem cells were mixed into GTAM bioinks for 3D bioprinting. The cell-laden 3D printed GTAM scaffolds showed biocompatibility and bone formation ability depending on MXene, crosslinked Sr²⁺, and β-TCP. In vivo, we implanted 3D printed GTAM scaffolds in S. aureus-infected mandible defects of rats with NIR irradiation. GTAM scaffolds could accelerate the healing of infection and bone regeneration, and play synergistic roles in antibacterial and osteogenic effects. This study not only provides a strategy for the precise osteogenesis of infected bone defects, but also broadens the biomedical applications of MXene photothermal materials.

Improved Tribocorrosion Behavior Obtained by In-Situ Precipitation of Ti2C in Ti-Nb Alloy

Novel in-situ Ti-based matrix composites (TMCs) were developed through the reactive hot pressing of Ti + NbC powder blends. Due to the chemical reaction that occurred in the solid-state during processing, the produced samples were composed of an Nb-rich β-Ti phase that formed a metallic matrix along with Ti2C as a reinforcing phase. By employing different proportions of Ti:NbC, the phase composition of the alloys was designed to contain different ratios of α-Ti and β-Ti. The present work investigated the corrosion and tribocorrosion behavior of the composites, compared to unreinforced Ti, in a phosphate-buffered solution (PBS) at body temperature. Corrosion tests included potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Tribocorrosion tests were carried out using a ball-on-plate tribometer with sliding performed at open circuit potential (OCP) and under anodic potentiostatic conditions. Results showed that the stabilization of the β phase in the matrix led to a decrease in the hardness. However, the formation of the in-situ reinforcing phase significantly improved the tribocorrosion behavior of the composites due to a load-carrying effect, lowering the corrosion tendency and kinetics under sliding. Furthermore, localized corrosion was not observed at the interface between the reinforcing phase and the matrix.

3D printing of Ti3C2-MXene-incorporated composite scaffolds for accelerated bone regeneration

Grafting of bone-substitute biomaterials plays a vital role in the reconstruction of bone defects. However, the design of bioscaffolds with osteoinductive agents and biomimetic structures for regeneration of critical-sized bone defects is difficult. Ti3C2 MXene-belonging to a new class of two-dimensional (2D) nanomaterials-exhibits excellent biocompatibility, and antibacterial properties, and promotes osteogenesis. However, its application in preparing 3D-printed tissue-engineered bone scaffolds for repairing bone defects has not been explored. In this work, Ti3C2 MXene was incorporated into composite scaffolds composed of hydroxyapatite (HA) and sodium alginate (SA) via extrusion-based 3D printing to evaluate its potential in bone regeneration. MXene composite scaffolds were fabricated and characterized by SEM, XPS, mechanical properties and porosity. The biocompatibility and osteoinductivity of MXene composite scaffolds were evaluated by cell adhesion, CCK-8 test, qRT-PCR, ALP activity and ARS tests of BMSCs. A rat calvarial defect model was performed to explore the osteogenic activity of the MXene composite scaffolds in vivo. The results showed the obtained scaffold had a uniform structure, macropore morphology, and high mechanical strength. In vitro experimental results revealed that the scaffold exhibited excellent biocompatibility with bone mesenchymal stem cells, promoted cell proliferation, upregulated osteogenic gene expression, enhanced alkaline phosphatase activity, and promoted mineralized-nodule formation. The experimental results confirmed that the scaffold effectively promoted bone regeneration in a model of critical-sized calvarial- bone-defect in vivo and promoted bone healing to a significantly greater degree than scaffolds without added Ti3C2 MXene did. Conclusively, the Ti3C2 MXene composite 3D-printed scaffolds are promising for clinical bone defect treatment, and the results of this study provide a theoretical basis for the development of practical applications for tissue-engineered bone scaffolds.

Success Factors of Additive Manufactured Root Analogue Implants

Dental implantation is an effective method for the treatment of loose teeth, but the threaded dental implants used in the clinic cannot match with the tooth extraction socket. A root analogue implant (RAI) has the congruence shape, which reduces the damage to bone and soft tissue. Additive manufacturing (AM) technologies have the advantages of high precision, flexibility, and easy operation, becoming the main manufacturing method of RAI in basic research. The purpose of this systematic review is to summarize AM technologies used for RAI manufacturing as well as the factors affecting successful implantation. First, it introduces the AM technologies according to different operating principles and summarizes the advantages and disadvantages of each method. Then the influences of materials, structure design, surface characteristics, implant site, and positioning are discussed, providing reference for designers and dentists. Finally, it addresses the gap between basic research and clinical application for additive manufactured RAIs and discusses the current challenges and future research directions for this field.

Ultrathin 2D Titanium Carbide MXene (Ti3 C2 Tx ) Nanoflakes Activate WNT/HIF-1α-Mediated Metabolism Reprogramming for Periodontal Regeneration

Periodontal defect regeneration in severe periodontitis relies on the differentiation and proliferation of periodontal ligament cells (PDLCs). Recently, an emerging 2D nanomaterial, MXene (Ti₃ C₂ T_x ), has gained more and more attention due to the extensive antibacterial and anticancer activity, while its potential biomedical application on tissue regeneration remains unclear. Through a combination of experimental and multiscale simulation schemes, Ti₃ C₂ T_x has exhibited satisfactory biocompatibility and induced distinguish osteogenic differentiation of human PDLCs (hPDLCs), with upregulated osteogenesis-related genes. Ti₃ C₂ T_x manages to activate the Wnt/β-catenin signaling pathway by enhancing the Wnt-Frizzled complex binding, thus stabilizing HIF-1α and altering metabolic reprogramming into glycolysis. In vivo, hPDLCs pretreated by Ti₃ C₂ T_x display excellent performance in new bone formation and osteoclast inhibition with enhanced RUNX2, HIF-1α, and β-catenin in an experimental rat model of periodontal fenestration defects, indicating that this material has high efficiency of periodontal regeneration promotion. It is demonstrated in this work that Ti₃ C₂ T_x has highly efficient therapeutic effects in osteogenic differentiation and periodontal defect repairment.

Microstructure and Corrosion Behavior of Ti-Nb Coatings on NiTi Substrate Fabricated by Laser Cladding

Ti-23Nb (at.%) coatings on an NiTi alloy with metallurgical bonding were prepared by laser cladding (LC) technology using Ti-Nb mixture powders. The effects of laser processing parameters on the microstructure and mechanical properties of the coatings were systematically investigated and the corrosion resistance of the coatings was assessed. The coatings were composed of TiNb, (Ti, Nb)2Ni, and β-Nb phases. The coatings increased the hardness of the NiTi alloy by a combined strengthening effect of the eutectics and fine microstructure. The corrosion resistance of the coated part was improved. The coatings with great corrosion resistance could keep the coated parts inert in an aggressive environment, and effectively restrain the release of toxic Ni ions, which means that the Ti-Nb alloy coatings are likely to be used as a biomaterial for medical applications.

A more defective substrate leads to a less defective passive layer: Enhancing the mechanical strength, corrosion resistance and anti-inflammatory response of the low-modulus Ti-45Nb alloy by grain refinement

Orthopedic and dental implants made of β-type Ti alloys have low elastic modulus which can better relieve the stress shielding effects after surgical implantation. Nevertheless, clinical application of β-type Ti alloys is hampered by the insufficient mechanical strength and gradual release of pro-inflammatory metallic ions under physiological conditions. In this study, the β-type Ti-45Nb alloy is subjected to high-pressure torsion (HPT) processing to refine the grain size. After HPT processing, the tensile strength increases from 370 MPa to 658 MPa due to grain boundary strengthening and at the same time, the favorable elastic modulus is maintained at a low level of 61-72 GPa because the single β-phase is preserved during grain refinement. More grain boundaries decrease the work function and facilitate the formation of thicker and less defective passive films leading to better corrosion resistance. In addition, more rapid repair of the passive layer mitigates release of metallic ions from the alloy and consequently, the inflammatory response is suppressed. The results reveal a strategy to simultaneously improve the mechanical and biological properties of metallic implant materials for orthopedics and dentistry. STATEMENT OF SIGNIFICANCE: The low modulus Ti-45Nb alloy is promising in addressing the complication of stress shielding induced by biomedical Ti-based materials with too-high elastic modulus. However, its insufficient strength hampers its clinical application, and traditional strengthening via heat treatments will compromise the low elastic modulus. In the current study, we enhanced the ultimate tensile strength of Ti-45Nb from 370 MPa to 658 MPa through grain-refinement strengthening, while the elastic modulus was maintained at a low value (61-72 GPa). Moreover, substrate grain-refinement has been proved to improve the corrosion resistance of Ti-45Nb with reduced inflammatory response both in vitro and in vivo. A relationship between the substrate microstructure and the surface passive layer has been established to explain the beneficial effects of substrate grain-refinement.

Advances in Laser Additive Manufacturing of Ti-Nb Alloys: From Nanostructured Powders to Bulk Objects

The additive manufacturing of low elastic modulus alloys that have a certain level of porosity for biomedical needs is a growing area of research. Here, we show the results of manufacturing of porous and dense samples by a laser powder bed fusion (LPBF) of Ti-Nb alloy, using two distinctive fusion strategies. The nanostructured Ti-Nb alloy powders were produced by mechanical alloying and have a nanostructured state with nanosized grains up to 90 nm. The manufactured porous samples have pronounced open porosity and advanced roughness, contrary to dense samples with a relatively smooth surface profile. The structure of both types of samples after LPBF is formed by uniaxial grains having micro- and nanosized features. The inner structure of the porous samples is comprised of an open interconnected system of pores. The volume fraction of isolated porosity is 2 vol. % and the total porosity is 20 vol. %. Cell viability was assessed in vitro for 3 and 7 days using the MG63 cell line. With longer culture periods, cells showed an increased cell density over the entire surface of a porous Ti-Nb sample. Both types of samples are not cytotoxic and could be used for further in vivo studies.

Modifying an Implant: A Mini-review of Dental Implant Biomaterials

Dental implants have been used as far back as 2000BC, and since then have developed into highly sophisticated solutions for tooth replacement. It is becoming increasingly important for the materials used in dental implants to exhibit and maintain favorable long-term mechanical, biological and more recently, aesthetic properties. This review aims to assess the biomaterials used in modern dental implants, introducing their properties, and concentrating on modifications to improve these biomaterials. Focus is drawn to the prominent biomaterials, titanium (Ti) and zirconia due to their prevalence in implant dentistry. Additionally, novel coatings and materials with potential use as viable improvements or alternatives are reviewed. An effective dental biomaterial should osseointegrate, maintain structural integrity, resist corrosion and infection, and not cause systemic toxicity or cytotoxicity. Current materials such as bioactive glass offer protection against biofilm formation, and when combined with a titanium‐zirconium (TiZr) alloy, provide a reliable combination of properties to represent a competitive alternative. Further long-term clinical studies are needed to inform the development of next-generation materials.Significance StatementBiomaterials have become essential for modern implants. A suitable implant biomaterial integrates into the body to perform a key function, whilst minimizing negative immune response. Focusing on dentistry, the use of dental implants for tooth replacement requires a balance between bodily response, mechanical structure and performance, and aesthetics. This mini-review addresses the use of biomaterials in dental implants with significant comparisons drawn between Ti and zirconia. Attention is drawn to optimizing surface modification processes and the additional use of coatings. Alternatives and novel developments are addressed, providing potential implications of combining biomaterials to form novel composites that combine and synergize the benefits of each material.

Ultrafine-Grained Ti-31Mo-Type Composites with HA and Ag, Ta2O5 or CeO2 Addition for Implant Applications

Ultrafine-grained Ti31Mo alloy and Ti31Mo5HA, Ti31Mo5HA-Ag (or Ta₂O₅, CeO₂) composites with a grain size of approximately 2 μm were produced by the application of mechanical alloying and powder metallurgy. Additionally, the surface of the Ti31Mo alloy was modified. In the first stage, the specimens were immersed in 5M NaOH for 24 h at 60 °C. In the second stage, hydroxyapatite (HA) was deposited on the sample surface. The cathodic deposition at −5 V vs. open circuit potential (OCP) in the electrolyte containing 0.25M CaNa₂-EDTA (di-calcium ethylenediaminetetraacetic acid), 0.25M K₂HPO₄ in 1M NaOH at 120 °C for 2 h was applied. The bulk Ti31Mo alloy is a single β-type phase. In the alkali-modified surface titanium oxide, Ti₃O is formed. After hydrothermal treatment, the surface layer mostly consists of the Ca₁₀(PO₄)₆(OH)₂ (81.23%) with about 19% content of CaHPO₄·2H₂O. Using optical profiler, roughness 2D surface topography parameters were estimated. The in vitro cytocompatibility of synthesized materials was studied. The cell lines of normal human osteoblasts (NHost) and human periodontal ligament fibroblasts (HPdLF) was conducted in the presence of tested biomaterials. Ultrafine-grained Ti-based composites altered with HA and Ag, Ta₂O₅ or CeO₂ have superior biocompatibility than the microcrystalline Ti metal. NHost and HPdLF cells in the contact with the synthesized biomaterial showed stable proliferation activity. Biocompatibility tests carried out indicate that the ultrafine-grained Ti31Mo5HA composites with Ag, Ta₂O_5, or CeO₂ could be a good candidate for implant applications.

Biocompatible High Entropy Alloys with Excellent Degradation Resistance in a Simulated Physiological Environment

Bioimplants are susceptible to simultaneous wear and corrosion degradation in the aggressive physiological environment. High entropy alloys with equimolar proportion of constituent elements represent a unique alloy design strategy for developing bioimplants due to their attractive mechanical properties, superior wear, and corrosion resistance. In this study, the tribo-corrosion behavior of an equiatomic MoNbTaTiZr high entropy alloy consisting of all biocompatible elements was evaluated and compared with 304 stainless steel as a benchmark. The high entropy alloy showed a low wear rate and a friction coefficient as well as quick and stable passivation in simulated body fluid. An increase from room temperature to body temperature showed excellent temperature assisted passivity and nobler surface layer of the high entropy alloy, resulting in four times better wear resistance compared to stainless steel. Stem cells and osteoblast cells displayed proliferation and migratory behavior, indicating in vitro biocompatibility. Several filopodia extensions on the cell periphery indicated early osteogenic commitment, and cell adhesion on the high entropy alloy. These results pave the way for utilizing the unique combination of tribo-corrosion resistance, excellent mechanical properties, and biocompatibility of MoNbTaTiZr high entropy alloy to develop bioimplants with improved service life and lower risk of implant induced cytotoxicity in the host body.

Comparative analysis of corrosion resistance between beta titanium and Ti-6Al-4V alloys: A systematic review

BACKGROUND

The knowledge of the electrochemical property (corrosion resistance) of beta titanium alloys compared to Ti-6Al-4 V for implants is relevant because of the potential cytotoxic effects that the released ions could cause to long-term health.

OBJECTIVES

The objective of this systematic review was to seek information on the electrochemical properties (corrosion resistance) of beta titanium alloys compared to Ti-6Al-4 V since the awareness of the electrochemical behavior of the implant surface in the medium is essential for the best indication of the alloys or compositional changes, which may promote benefits to bone-implant interaction in all areas that this procedure is required.

METHODS

The PubMed, LILACS, COCHRANE Library, and Science Direct databases were electronically searched for the terms: dental implants AND beta-titanium AND Ti-6Al-4 V AND electrochemical technics. The inclusion criteria were research articles that studied beta-titanium compared to Ti-6Al-4 V using electrochemical techniques in electrolytes of chemical composition similar to body fluid, published in English, between 2000 and 2020. Articles that did not compare the corrosion resistance of these alloys in electrolytes similar to body fluids were excluded.

RESULTS

A total of 189 articles were restored and selected by title and/or abstract according to the inclusion and exclusion criteria, which resulted in 15 articles that were reduced to 8 after read in full. The studies in vitro evaluated the corrosion resistance in electrolytes Hank, Ringer, SBF, and 0.9 % NaCl, between beta titanium alloys, obtained by arc fusion or bars stock, and Ti-6Al-4 V, for dental or biomedical implants submitted to surface treatments by heat treatment, plasma electrolytic oxidation (PEO), alkaline treatment, and thermomechanical.

CONCLUSION

The evaluated literature allowed to determine that 1) The oxides Nb₂O ₅, Ta₂O _5, and ZrO₂ have higher stability and protection quality than that of TiO₂ modified by the oxides of Al and V; 2) A higher modulus of elasticity of the Ti-6Al-4 V alloy favors protection against corrosion by maintaining a thicker and more firmly adhered oxide layer; 3) The increase in the thickness of the Ti alloys superficial layer contributes to the improvement of the corrosion resistance.

Advancements in Therapeutics via 3D Printed Multifunctional Architectures from Dispersed 2D Nanomaterial Inks

2D nanomaterials (2DNMs) possess fascinating properties and are found in multifarious devices and applications including energy storage devices, new generation of battery technologies, sensor devices, and more recently in biomedical applications. Their use in biomedical applications such as tissue engineering, photothermal therapy, neural regeneration, and drug delivery has opened new horizons in treatment of age-old ailments. It is also a rapidly developing area of advanced research. A new approach of integrating 3D printing (3DP), a layer-by-layer deposition technique for building structures, along with 2DNM multifunctional inks, has gained considerable attention in recent times, especially in biomedical applications. With the ever-growing demand in healthcare industry for novel, efficient, and rapid technologies for therapeutic treatment methods, 3DP structures of 2DNMs provide vast scope for evolution of a new generation of biomedical devices. Recent advances in 3DP structures of dispersed 2DNM inks with established high-performance biomedical properties are focused on. The advantages of their 3D structures, the sustainable formulation methods of such inks, and their feasible printing methods are also covered. Subsequently, it deals with the therapeutic applications of some already researched 3DP structures of 2DNMs and concludes with highlighting the challenges as well as the future directions of research in this area.

Composite and Surface Functionalization of Ultrafine-Grained Ti23Zr25Nb Alloy for Medical Applications

In this study, the ultrafine-grained Ti23Zr25Nb-based composites with 45S5 Bioglass and Ag, Cu, or Zn additions were produced by application of the mechanical alloying technique. Additionally, the base Ti23Zr25Nb alloy was electrochemically modified in the two stages of processing: electrochemical etching in the solution of H₃PO₄ and HF followed by electrochemical deposition in Ca(NO₃)₂, (NH₄)₂HPO₄, and HCl. The in vitro cytocompatibility studies were also done with comparison to the commercially pure titanium. The established cell lines of Normal Human Osteoblasts (NHost, CC-2538) and Human Periodontal Ligament Fibroblasts (HPdLF, CC-7049) were used. The culture was conducted among the tested materials. Ultrafine-grained titanium-based composites modified with 45S5 Bioglass and Ag, Cu, or Zn metals have higher biocompatibility than the reference material in the form of a microcrystalline Ti. Proliferation activity was at a stable level with contact with studied materials. In vitro evaluation research showed that the ultrafine-grained Ti23Zr25Nb-based composites with 45S5 Bioglass and Ag, Cu, or Zn additions, with a Young modulus below 50 GPa, can be further used in the biomedical field.

Bond strength of commercial veneering porcelain to experimental cast Ti-Cr alloy

This study evaluated bond strengths of three commercial veneering porcelains to experimental cast titanium-chromium (Ti-Cr) alloy and commercially pure titanium (cp-Ti) via three-point bending test. After the bending test, the fractured specimens were analyzed using an electron probe microanalyzer (EPMA). The Ti-Cr specimens showed lower bond strengths than the cp-Ti specimens, irrespective of the layering porcelain material; however, all the strengths exceeded the minimum requirement of ISO 9693-1:2012 (>25 MPa). EPMA revealed that titanium and/or chromium elements were detected on the debonded porcelain surface of the Ti-Cr and cp-Ti specimens in the case of the higher bond strength. Contrastingly, the residual porcelain was retained on the metallic surface in the case of the lower bond strength. Although porcelain bonding to the titanium alloy is influenced by porcelain type, the Ti-Cr alloy could be feasible for porcelain-fused-to-metal restorations.

Fabrication, characterization, and in vivo biocompatibility evaluation of titanium-niobium implants

In this study, biocompatible titanium-niobium (Ti-Nb) alloys were fabricated by using powder metallurgy methods. Physical, morphological, thermal, and mechanical analyses were performed and their in vivo compatibility was evaluated. Besides α, β, and α″ martensitic phases, α+β Widmanstätten phase due to increasing sintering temperature was seen in the microstructure of the alloys. Phase transformation temperatures of the samples decreased as Nb content increased. The ratio of Nb in the samples affected their mechanical properties. No toxic effect was observed on implanted sites. This study shows that Ti-Nb alloys can be potentially used for orthopedic applications without any toxic effects.

Influence of Titanium Alloy Scaffolds on Enzymatic Defense against Oxidative Stress and Bone Marrow Cell Differentiation

Studies have been directed towards the production of new titanium alloys, aiming for the replacement of Ti-6 Aluminium-4 Vanadium (TiAlV) alloy in the future. Many mechanisms related to biocompatibility and chemical characteristics have been studied in the field of implantology, but enzymatic defenses against oxidative stress remain underexplored. Bone marrow stromal cells have been explored as source of cells, which have the potential to differentiate into osteoblasts and therefore could be used as cells-based therapy. The objective of this study was to evaluate the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in porous scaffolds of Ti-6 Aluminium-4 Vanadium (TiAlV), Ti-35 Niobium (TiNb), and Ti-35 Niobium-7 Zirconium-5 Tantalum (TiNbZrTa) on mouse bone marrow stromal cells. Porous titanium alloy scaffolds were prepared by powder metallurgy. After 24 hours, cells plated on the scaffolds were analyzed by scanning electron microscopy (SEM). The antioxidant enzyme activity was measured 72 hours after cell plating. Quantitative real time PCR (qRT-PCR) was performed after 3, 7, and 14 days, and Runx2 (Runt-related transcription factor2) expression was evaluated. The SEM images showed the presence of interconnected pores and growth, adhesion, and cell spreading in the 3 scaffolds. Although differences were noted for SOD and CAT activity for all scaffolds analyzed, no statistical differences were observed (p > 0.05). The osteogenic gene Runx2 presented high expression levels for TiNbZrTa at day 7, compared to the control group (TiAlV day 3). At day 14, all scaffolds had more than 2-fold induction for Runx2 mRNA levels, with statistically significant differences compared to the control group. Even though we were not able to confirm statistically significant differences to justify the replacement of TiAlV regarding antioxidant enzymes, TiNbZrTa was able to induce faster bone formation at early time points, making it a good choice for biomedical and tissue bioengineering applications.

The effect of laser frequency on roughness, microstructure, cell viability and attachment of Ti6Al4V alloy

Titanium alloys are commonly used in orthopedic devices due to their good corrosion resistance, high specific strength and excellent biological response. The direct contact between the implant surface and the host tissue results in notable effect of surface properties such as surface topography on the biological responses. The aim of this study is to investigate the effect of frequency of pulsed Nd-YAG laser on Ti6Al4V alloy surface topography and its influence on the improvement of biocompatibility while other laser parameters kept constant. The range of applied frequency values were selected from 1 to 20 Hz. The range of surface roughness was found between 452 nm and 3.37 μm. The untreated sample and also samples with the highest and the lowest average surface roughness parameter were subjected to the further analyses. Characterization of the samples was performed with surface roughness tester, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The high rate of melt and solidification during the laser treatment led to the martensite formation and consequently an increase about 12-25% in hardness. Furthermore, in vitro study was carried out using MG-63 osteoblast like cells. The analyses of cell viability for 3 culture times, cell morphology and cell spreading area revealed that sample with the highest average surface roughness parameter is more biocompatible. 10 Hz frequency was found as the optimum parameter which led to the highest surface roughness and thus the biocompatibility enhancement. In conclusion, the pulsed Nd-YAG laser with an optimum value of applied frequency can be utilized as an effective technique to improve the biological characteristics.

Influence of chemical composition on cell viability on titanium surfaces: A systematic review

STATEMENT OF PROBLEM

A consensus on which dental implant alloy and surface treatment provide the best cell viability is unclear.

PURPOSE

The purpose of this systematic review was to provide information on the influence of surface and intrinsic titanium alloy chemical components on cell viability.

MATERIAL AND METHODS

The PubMed, LILACS, COCHRANE library, and Science Direct databases were electronically searched for the terms dental implants AND titanium AND cytotoxicity. Inclusion criteria were research articles that studied titanium or its alloys for chemical composition and cell viability and were published in English between 1999 and 2019. Articles that did not study titanium and its alloys, articles with nondental or biomedical implants, and articles that were not found in their entirety were excluded.

RESULTS

A total of 1226 articles selected by title or abstract according to the inclusion and exclusion criteria resulted in 51 articles that were reduced to 27 after reading in full. The treatments analyzed were arc fusion, electron beam physical deposition, plasma electrolytic oxidation, coating addition, micro arc oxidation, anodization, thermochemical process, BMP-2 immobilization, pressure-assisted sintering, and alkali heat treatment.

CONCLUSIONS

The evaluated literature did not allow a determination of the best surface treatment for cell viability because of the heterogeneity of the studies regarding the type of alloy, cell used in the MTT assay, study, and implant purpose (biomedical or dental). The cytotoxic effect of chemical components was dependent on dose, time, size, temperature, and cell type. The niobium, tantalum, zirconium, and molybdenum elements have been most often added in the development of less toxic Ti alloys with lower modulus of elasticity and increased strength.

2D MXene-Integrated 3D-Printing Scaffolds for Augmented Osteosarcoma Phototherapy and Accelerated Tissue Reconstruction

The residual of malignant tumor cells and lack of bone-tissue integration are the two critical concerns of bone-tumor recurrence and surgical failure. In this work, the rational integration of 2D Ti3C2 MXene is reported with 3D-printing bioactive glass (BG) scaffolds for achieving concurrent bone-tumor killing by photonic hyperthermia and bone-tissue regeneration by bioactive scaffolds. The designed composite scaffolds take the unique feature of high photothermal conversion of integrated 2D Ti3C2 MXene for inducing bone-tumor ablation by near infrared-triggered photothermal hyperthermia, which has achieved the complete tumor eradication on in vivo bone-tumor xenografts. Importantly, the rational integration of 2D Ti3C2 MXene is demonstrated to efficiently accelerate the in vivo growth of newborn bone tissue of the composite BG scaffolds. The dual functionality of bone-tumor killing and bone-tissue regeneration makes these Ti3C2 MXene-integrated composite scaffolds highly promising for the treatment of bone tumors, which also substantially broadens the biomedical applications of 2D MXenes in tissue engineering, especially on the treatment of bone tumors.

Mechanical aspects of dental implants and osseointegration: A narrative review

With the need of rapid healing and long-term stability of dental implants, the existing Ti-based implant materials do not meet completely the current expectation of patients. Low elastic modulus Ti-alloys have shown superior biocompatibility and can achieve comparable or even faster bone formation in vivo at the interface of bone and the implant. Porous structured Ti alloys have shown to allow rapid bone ingrowth through their open structure and to achieve anchorage with bone tissue by increasing the bone-implant interface area. In addition to the mechanical properties of implant materials, the design of the implant body can be used to optimize load transfer and affect the ultimate results of osseointegration. The aim of this narrative review is to define the mechanical properties of dental implants, summarize the relationship between implant stability and osseointegration, discuss the effect of metallic implant mechanical properties (e.g. stiffness and porosity) on the bone response based on existing in vitro and in vivo information, and analyze load transfer through mechanical properties of the implant body. This narrative review concluded that although several studies have presented the advantages of low elastic modulus or high porosity alloys and their effect on osseointegration, further in vivo studies, especially long-term observational studies are needed to justify these novel materials as a replacement for current Ti-based implant materials.

Mechanical and biological properties of Ti-(0-25 wt%)Nb alloys for biomedical implants application

Binary titanium–niobium (Ti–Nb) alloys have recently been attracted due to low Young’s moduli and non-toxic properties. This study explores the influence of low Nb content (0–25 wt%) on the comprehensive parameters of tensile stress–strain relationships (ultimate strength (σ_UTS), yield strength (σ_0.2) and elastic modulus (E)), surfaces properties (Vickers microhardness, surface roughness (R_a), water contact angle (WCA), X-ray diffraction (XRD) and scanning electron microscopy (SEM)), corrosion resistance (in artificial saliva and lactic acid) and biological properties (cytotoxicity and alkaline phosphatase activity of MC3T3-E1 pre-osteoblasts) of Ti–xNb alloys (x = 5, 10, 15, 20 and 25 wt%), with using commercially pure grade 2 titanium (cp-Ti) as control. XRD results shown that all the Ti–xNb alloys comprised α + β Ti alloy phases, such that the β phase increased correspondingly with the increased amount of Nb in the alloy, as well as the reduction of E (69–87 GPa). Except Ti–5Nb, all other Ti–xNb alloys showed a significantly higher hardness, increased σ_UTS and σ_0.2, and decreased WCA compared with cp-Ti. No corrosion was detected on Ti–xNb alloys and cp-Ti in artificial saliva and lactic acid solutions. The cytotoxicity of Ti–xNb alloys was comparable to that of cp-Ti in MC3T3-E1 pre-osteoblasts without interference from differentiation behaviour, but the proliferation rate of the Ti–5Nb alloy was lower than other groups. In overall, binary Ti–(10–25 wt%)Nb alloys are promising candidate for orthopaedic and dental implants due to their improved mechanical properties and comparable biological performance, while Ti–5Nb should be used with caution.

A MGI-oriented investigation of the Young's modulus and its application to the development of a novel Ti-Nb-Zr-Cr bio-alloy

Young's modulus is essential for the design and production of the alloys. Thus, we proposed a MGI (Materials Genome Initiative)-oriented strategy for the high-throughput development of Young's modulus databank in the single-phase alloys. In this study, 17 diffusion couples of the bcc Ti-rich Ti-Nb-Zr, Ti-Nb-Cr and Ti-Nb-Zr-Cr systems annealed at 1273 K for 25 h were experimentally prepared. Subsequently, the composition-dependent Young's moduli and hardness in the bcc Ti-rich Ti-Nb-Zr-Cr system were determined by combining the nanoindentation technique and the electron probe micro analysis (EPMA). Moreover, on the basis of the presently obtained experimental data, the Young's modulus databank in the bcc Ti-Nb-Zr-Cr system were established by means of the CALPHAD (CALculation of PHAse Diagrams) approach. Finally, the Ti-22.6 at.% Nb-30 at.% Zr-3.8 at.% Cr alloy was designed from the Young's modulus databank and verified by using the nanoindentation and cytotoxicity tests. The results reveal that the present MGI-oriented strategy with the combination of the high-throughput measurements and the CALPHAD approach is a very effective method to accelerate the design/development of novel bio-Ti alloys.

Influence of nanoporous titanium niobium alloy surfaces produced via hydrogen peroxide oxidative etching on the osteogenic differentiation of human mesenchymal stromal cells

Titanium niobium alloys exhibit a lower stiffness compared to Ti6Al4V, the 'gold standard' for load-bearing bone implants. Thus, the critical mismatch in stiffness between the implant and adjacent bone tissue could be addressed with TiNb alloys and thereby reduce stress shielding, which can result in bone resorption and subsequent implant loosening; however, the cellular response on the specific material is crucial for sufficient osseointegration. We therefore hypothesize that the response of human mesenchymal stromal cells (hMSC) and osteoblast-like cells on Ti45Nb surfaces can be improved by a novel nanoporous surface structure. For this purpose, an etching technique using hydrogen peroxide electrolyte solution was applied to Ti45Nb. The treated surfaces were characterized using SEM, LSM, AFM, nanoindentation, and contact angle measurements. Cell culture experiments using hMCS and MG-63 were conducted. The H₂O₂ treatment resulted in surface nanopores, an increase in surface wettability and a reduction in surface hardness. The proliferation of MG-63 was enhanced on TiNb45 compared to Ti6Al4V. MG-63 focal adhesion complexes were detected on all Ti45Nb surfaces, whereas the nanostructures notably increased the cell area and decreased cell solidity, indicating stimulated cell spreading and pseudopodia formation. Alizarin red stainings indicated that the nanoporous surfaces stimulated the osteogenic differentiation of hMSC. It can be concluded that the proposed surface treatment could potentially help to stimulate the osseointegration behaviour of the advantageous low stiff Ti45Nb alloy.